Post-disaster food aid saves lives, but it can also undercut local merchants critical to the supply chain. FRONTLINE/World and NPR’s Planet Money reporter Adam Davidson explores this predicament in “Haiti: The Aid Dilemma,” the latest in a series of economic reports from post-earthquake Haiti.

The story airs as the second of three magazine-length segments in this week’s episode of FRONTLINE/World. In advance of the broadcast, we are previewing the segment on the Web and inviting viewers to post questions and comments. Davidson will be responding to the postings the day of the broadcast: today, June 29, from 11 a.m. to noon.